//  FitnessAndCrowdingDistanceComparator.java
//
//  Author:
//       Antonio J. Nebro <antonio@lcc.uma.es>
//       Juan J. Durillo <durillo@lcc.uma.es>
//
//  Copyright (c) 2011 Antonio J. Nebro, Juan J. Durillo
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU Lesser General Public License for more details.
// 
//  You should have received a copy of the GNU Lesser General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.

package etmo.util.comparators;

import java.util.Comparator;

/**
 * This class implements a <code>Comparator</code> (a method for comparing
 * <code>Solution</code> objects) based on the fitness and crowding distance.
 */
public class FitnessAndCrowdingDistanceComparator implements Comparator {

	/**
	 * stores a comparator for check the fitness value of the solutions
	 */
	private static final Comparator fitnessComparator_ = new FitnessComparator();
	/**
	 * stores a comparator for check the crowding distance
	 */
	private static final Comparator crowdingDistanceComparator_ = new CrowdingDistanceComparator();

	/**
	 * Compares two solutions.
	 * 
	 * @param solution1
	 *            Object representing the first <code>Solution</code>.
	 * @param solution2
	 *            Object representing the second <code>Solution</code>.
	 * @return -1, or 0, or 1 if solution1 is less than, equal, or greater than
	 *         solution2, respectively.
	 */
	public int compare(Object solution1, Object solution2) {

		int flag = fitnessComparator_.compare(solution1, solution2);
		if (flag != 0) {
			return flag;
		} else {
			return crowdingDistanceComparator_.compare(solution1, solution2);
		}
	} // compares
} // FitnessAndCrowdingDistanceComparator
